Processes for the separation of components in a mixture are numerous, and one such process that is commonly used is distillation, which effects the separation of components based on differences in their respective volatilities. Azeotropic mixtures, in which the components have the same vapor phase and liquid phase composition, and close-boiling mixtures cannot, however, be easily separated by conventional distillation. To remedy this situation, a process that is often used for separating a mixture of components that have similar boiling points is extractive distillation, in which an entrainer is added to the mixture to selectively interact with one or more of the components of the mixture so that separation of the other component(s) is made possible. Seiler et al [Amer. Inst. Chem. Engrs J. (2004) 50:2439-2453] describe the use of an ionic liquid as an entrainer in extractive distillation for the separation of the azeotropic systems ethanol-water and THF-water. U.S. Patent Application 2004/0133058 also describes a process for separating close-boiling, and homo- and hetero-azeotropic mixtures by the use of ionic liquids.
A need still remains, however, for improved processes to be used for the separation of components in azeotropic or close-boiling mixtures that contain at least one hydrofluorocarbon compound.